Objective: To study the morphologic features, immunophenotype and significance of expression of JAZF1-SUZ12 and YWHAE-FAM22 fusion genes in endometrial stromal sarcoma (ESS).
Methods: Fifty-three cases of ESS were retrieved and the pathologic features were reviewed. Immunohistochemical study for estrogen receptor, progesterone receptor, CD10, cyclin D1, smooth muscle actin, desmin and H-caldesmon were carried out using tissue microarray technology. Reverse transcription-polymerase chain reaction (RT-PCR) was applied for detection of expression of JAZF1-SUZ12 and YWHAE-FAM22 fusion genes in 47 cases of ESS and 12 cases of other spindle cell neoplasia in uterus (including 2 cases of undifferentiated sarcoma, 3 cases of leiomyosarcoma, 3 cases of leiomyoma, 4 cases of adenosarcoma and 2 cases of uterine tumor resembling ovarian sex cord tumor).
Results: The 53 cases of ESS studied included 43 cases of low-grade ESS and 10 cases of high-grade ESS. As for low-grade ESS, in addition to the classic morphologic features, smooth muscle differentiation was present in 7 cases (16.3%), sex cord-like differentiation in 2 cases (4.7%), rhabdoid differentiation in 1 case (2.3%), clear cell changes in 1 case (2.3%) and schwannoma-like palisading pattern in 1 case (2.3%). As for high-grade ESS, sex cord-like differentiation (1 case), mucinous microcystic changes (1 case) and focal clear cell changes (1 case) were also observed. The expression rate of estrogen receptor, progesterone receptor, CD10, cyclin D1, smooth muscle actin, desmin and H-caldesmon was 86.0%, 81.4%, 74.4%, 2.3%, 23.3%, 23.3% and 4.7% in low-grade ESS, respectively, and was 1/10, 6/10, 6/10, 7/10, 1/10, 1/10 and 0 in high-grade ESS, respectively. RNA extraction was successful in 47 cases of ESS, including 39 cases of low-grade ESS and 8 cases of high-grade ESS. The positive rate of JAZF1-SUZ12 fusion gene was 30.8% (12/39) in low-grade ESS. The positive rate of YWHAE-FAM22 fusion gene was 12.5% (1/8) in high-grade ESS. The 14 control cases were all negative for JAZF1-SUZ12 and YWHAE-FAM22 fusion genes.
Conclusions: As uncommon pathologic pattern may occur in both low-grade ESS and high-grade ESS, detection of JAZF1-SUZ1 and YWHAE-FAM22 fusion genes by RT-PCR would be helpful in diagnosis and differential diagnosis of ESS, especially for those tumors which lack typical morphologic features.